Sea to Summit Reactor sleeping bag liner review: extra insulation with a great warmth-to-weight ratio
Meet the reviewer
Sea to Summit Reactor sleeping bag liner: first impressions
When I received the Sea to Summit Reactor sleeping bag liner, I first wondered whether it would really be a necessary piece of kit.
Usually, a sleeping bag liner isn’t something I’d routinely update, seeming such a perfunctory piece of kit, necessary only for backpacking on multi-day adventures or traveling around bedbug-ridden hostels to avoid sleeping under suspiciously old bedding. But when I tested the Reactor liner, valley camping on the cold floor of a campsite in the Dolomites, wild camping in Ireland on a breezy coastal path, and on an expedition below the north face of a peak in Tajikistan, I noted just how relieved I was to have an extra insulation barrier to keep warm.
Specifications
• List price: $74.95 / £55 (compact)
• Packed size: 15 x 7 x 11cm / 5.9 x 2.8 x 4.3in
• Length: 198cm / 78in (compact); 216cm / 85in (regular)
• Weight: 268g / 9.5oz (compact); 284g / 10oz (regular)
• Colors: Black (old model) / Yellow
• Compatibility: Travel, hiking, multi-day activity
Out came the sleeping bag liner – no fuss or extra faff other than slipping myself inside with a hood to flip over the top of my head, and easily adaptable to my mummy-shaped sleeping bag. The sleeping bag liner also eliminated the dreaded ‘cold pocket’ feeling that sometimes happens if like me you’re smaller than the average man the sleeping bag is built for, so it makes a massive difference to the overall comfort factor.
Sea to Summit Reactor sleeping bag liner: on the trails
First things first, the Sea to Summit Reactor sleeping bag liner is compact and easy to store. It comes in a little drawstring pouch so it can be easily packed away. This takes up very little space – around the size of an apple. It’s super handy when every gram and inch of packing space is crucial, as the sleeping bag liner easily folds away and can even be tucked inside your sleeping bag, meaning it’s less likely to be forgotten about.
Sizing wise, it fits most sleeping bags, and newer models have a drawstring opening at the top and bottom to make visits to the loo easier – so you can keep the liner on and hitch it up for emergency toilet breaks without loss of heat from the body. It also allows sleepers who need more room to stretch the option to have their arms outside of the sleeping bag liner.
The Sea to Summit Reactor sleeping bag liner uses several different fabric technologies to help it keep fresh for multi-day use. HeiQ Fresh odor technology doesn’t rely on harmful chemicals such as biocides, nor does it contain any silver like Polygene. Treating the fabric with a bio-based Amino Sugar Polymer, the HeiQ is a clever chemical that controls odor build-up by neutralizing it. It permanently binds smelly molecules without affecting the fabric’s breathability, color, feel or wicking properties. This means the liner requires less washing, which overall is better for the environment, and is a much more practical sleeping fabric than standard cotton.
The Reactor liner also uses a cleverly engineered fabric known as Thermolite Pro. This is easy to move in, feeling like a comfortable fabric you’d want to fall asleep against, thanks to its knitted construction which yields great stretch and freedom of movement. The hollow core fibers have infrared-absorbing ceramic pigments that reflect body heat back in for greater heat retention. The fibers have also been recycled from 100% textile waste, and are GRS-certified, yet offer the same quality and durable lightweight warmth as their polymer virgin counterparts – just with a lower carbon footprint.
It’s really a no-brainer to carry a warmth-retaining sleeping bag liner. There are many ways to retain heat while wild camping – a decent insulation setup from the ground using a good sleeping pad, a carby meal at dinner, and use of a good hat to keep heat loss at bay all help. But for an extra guarantee that the night’s sleep will be a cozy one, the Reactor sleeping bag liner offered great peace of mind that I would stay as warm through the night as when I first got into the sleeping bag, and would wake up well rested.
